In order to energize a food material(s), heat for cooking it by Joule heat, and heat for sterilizing it while the food material having liquidity is conveyed through a flow path in a pipe, a continuous heat-treating apparatus disclosed in Patent Document 1 (Japanese Patent Application Laid-open No. 2001-169734) and a Joule heating apparatus disclosed in Patent Document 2 (Japanese Patent Application Laid-open No. 2015-156349) have been developed. A continuous heat-treating apparatus for food material includes a ring electrode type, an internal/external electrode type, and a flat plate type. Patent Document 1 discloses continuous energizing/heating apparatuses having the ring electrode and internal/external electrode types, and Patent Document 2 discloses a Joule heating apparatus having the ring electrode type. Further, Patent Document 3 (Japanese Patent Application Laid-open No. 2009-5583) discloses an AC high-electric-field sterilizing apparatus having the flat plate type.
The ring electrode type has heating pipes that are formed by a plurality of annular electrodes and a plurality of cylindrical spacers each made of an insulating material. While a food material(s) is caused to flow through each food channel in the heating pipes, the ring electrode type carries a current axially and between the annular electrodes axially adjacent to each other and energizes and heats the food material by Joule heat. In the ring electrode type, the cylindrical spacers each made of a resin form the food channel. The internal/external electrode type has a heating pipe, which is formed by a cylindrically-shaped outer electrode and a bar-shaped inner electrode placed inside the outer electrode and concentrically with the outer electrode. While a food material(s) is caused to flow in a tubular food flow channel(s) formed between the outer and inner electrodes, the internal/external electrode type carries a current radially, i.e., laterally between the outer and inner electrodes and energizes and heats the food material by Joule heat. Additionally, the flat plate type has electrode plates arranged on both surfaces of a plate-like spacer made of a resin. While a food material(s) is caused to flow in a food flow channel(s) formed by the both electrode plates and the plate-like spacer, the flat plate type carries a current between the opposite electrodes and energizes and heats the food material. Also in the flat plate type, the plate-like spacer made of a resin forms the food channel.
Thus, the apparatus, which heats the food material by Joule heat while the food material is caused to flow in the food flow channel, has the following advantage in comparison with a case of indirectly heating a food material(s) by hot water or steam. While the food material is caused to flow in the food flow channel, the food material can be heated in a short time and efficiently.